GridGroupingControl and "Object reference not set"

[Olivier Mayo]

I use, in my application, a grid grouping control. I bind data to it using the "DataSource" property. I trap the "QueryCellStyleInfo" event to change cell color and set if the cells are editable or not (using "enabled" and "readOnly" properties). So, basicilly, I bind data from the database to it, the user modifies the required cells and the application then updates the database consequently.

It used to work fine when I was only binding the data to it (without the "editing" portion done), but it now has a weird behavior. The only significant thing I changed is that I now handle the "TableControlCurrentCellEditingComplete" event, which recalculates my row totals and sets the cell values using
ggc.TableModel(iRow, iCol).CellValue = dNewValue

Here is what happends :
If I click on any editable cell and it gets the focus (with the ''I'' cursor) and hit TAB, it shows a message box that says "Object reference not set to an instance of an object". I checked and that error is not fired in the "TableControlCurrentCellEditingComplete" event (it occurs after, and not in my code). It looks like if the grid itself shows that message. However, if I modify the content of ONE cell and THEN hit TAB, everything is fine for all editable cells.

Got any clues?

[Administrator]

Can you set teh debugger to stop on exception, an dthen post the callstack?

I suspect the problem is that setting ggc.TableModel(iRow, iCol).CellValue = dNewValue at this point may be triggerring teh exception. I fyou comment out this line, does the problem go away?

If so, you can try few things like setting the value directly in your DataSource and not in the grid. Or, you set a flag in this event to indicate that you need to do your calculations, and then check this flag in TableControlCurrentCellMoved to see if setting teh value there works better.

[Administrator]

Hi Olivier,

try also handling the SourceListListChanged event. This event is called when the grid receives a IBindingList.ListChanged event.

By default if the current record is modified from the outside the current cell gets deactivated. My suspicion is that this is your problem (and a subsequent call in the CurrentCell code after you event returns then suddenly has no current cell anymore and has null ref problem).

When you handle that event you can instruct the grid not to deavtivate the current record by setting

e.ShouldResetCurrentRecord = false;

Stefan

[Olivier Mayo]

You were right...
The line ggc.TableModel(iRow, iCol).CellValue = dNewValue is the one that throws the exception. I''ll try your suggestions and will keep you informed ;)

[Olivier Mayo]

Thanks a lot Clay ;)
It worked fine!!! You''re a genius!!!

There''s only one other problem I just can''t solve... When I press TAB in a cell, I want the summary row to fresh automatically. The only way it does it is if I press ENTER and then press TAB. Is there any way to force the "commitment" of the cell content so that the summary row refreshes properly?

Thank you again ;)

[Administrator]

You can try calling:

groupingGrid.Table.TableDirty = true;
groupingGrid.Table.SummariesDirty = true;

before setting the value to see if this makes things to refresh.

[Olivier Mayo]

WOW!
You''re my new God Clay!!! :)

[Olivier Mayo]

I still get a problem with "Object reference not set" in my grouping grid control :(

I modified my code so that I affect the data source instead of setting the value of the cells manually. I can now navigate through the cells without problems using the mouse and TAB key, but I get the same error as before ("Object reference not set") if I use the left/right keys. Did I forget something???

Here''s my code :

''When we''re done editing the cell
Private Sub ggcFacturation_TableControlCurrentCellEditingComplete(ByVal sender As Object, ByVal e As Syncfusion.Windows.Forms.Grid.Grouping.GridTableControlEventArgs) Handles ggcFacturation.TableControlCurrentCellEditingComplete
If e.TableControl.CurrentCell.ColIndex = Me.COL_FACTURATION_AVANCEMENT_NUM Then
CalculateFieldsFacturation(e.TableControl.CurrentCell.RowIndex)
End If
End Sub

''Calculte fields in function of the record data at row iRow
Private Sub CalculateFieldsFacturation(ByVal iRow As Int32)

Dim dPrixVente As Decimal
Dim dAvancement As Decimal
Dim dNouveauCumul As Decimal
Dim dAFacturer As Decimal

dPrixVente = ggcFacturation.TableModel(iRow, COL_FACTURATION_PRIX_VENTE_NUM).CellValue
dAvancement = ggcFacturation.TableModel(iRow, COL_FACTURATION_AVANCEMENT_NUM).CellValue
dNouveauCumul = dAvancement / 100.0 * dPrixVente
dAFacturer = dNouveauCumul - ggcFacturation.TableModel.Item(iRow, COL_FACTURATION_DEJA_FACTURE_NUM).CellValue

''Force the summary row refresh
ggcFacturation.Table.TableDirty = True
ggcFacturation.Table.SummariesDirty = True

''Modify cell data
ggcFacturation.TableControl.Table.BeginEdit()
ggcFacturation.TableControl.Table.CurrentRecord.SetValue(COL_FACTURATION_NOUVEAU_CUMULATIF, dNouveauCumul.ToString)
ggcFacturation.TableControl.Table.CurrentRecord.SetValue(COL_FACTURATION_A_FACTURER, dAFacturer.ToString)
ggcFacturation.TableControl.Table.EndEdit()
ggcFacturation.TableControl.Refresh()

End Sub

[Administrator]

Did you try Stefan''s suggestion above, handling SourceListListChanged and setting e.ShouldResetCurrentCell = false?

[Olivier Mayo]

I''ld love to, but this property does not exist when I trap the event in my grid grouping control

[Administrator]

Are you using 2.1.0.9, the latest release? You can get it from your direct trac home page.

[Pat]

No, but I found the solution to my problem...

My problem never occured when I was modifying the row I am currently editing. However, I wanted to update rows I am not editing in function of the cell I just modified. Here''s what I did...

* Note that ROW_COUNT is a constant that stores the number of rows for each record. Basically, in my case, my grid will have 18 rows for 2 records (6 rows for the header, and then 6 rows for each record).

So here''s the code :

''Calculate the RECORD row based on the GRID row
Dim iRecordRow As Int32 = Math.Ceiling(iRow / ROW_COUNT) - 2

''Begin editing the record I wish to modify
ggcBudget.TableControl.Table.Records(iRecordRow).BeginEdit()

''Modify the cell value
ggcBudget.TableModel.Item(iGridRow, iGridCol).CellValue = myNewValue

''We''re done editing
ggcBudget.TableControl.Table.Records(iRecordRow).EndEdit()